It is important to be able to accurately and reliably measure the concentration of sulfur in liquids, as various chemical reactions may take place that can release harmful sulfur compounds into the atmosphere or onto physical structures around the sulfur-containing liquid. For example, the combustion of diesel fuel typically generates sulfur oxides (SO2, SO3) and sulfuric acid (H2SO4), which are components of acid rain and subject to environmental regulations. Further, these sulfur compounds have been linked to catalyst poisoning in diesel particulate filters (DPFs) and sulfuric acid may corrode engine components, such as the cooler and piston ring liner components. These phenomena may occur when using both high sulfur (>350 ppm) and low sulfur (15-350 ppm) fuels.
For these reasons, including the sensitivity of after-treatment components to sulfur compounds, modern diesel engines are now being designed to use ultra low sulfur diesel (ULSD) fuel (<15 ppm S). As a result of these design changes, a low sulfur concentration in diesel fuel is now imperative for optimum performance of many modern diesel engines. While sulfur detection in liquids at levels below 15 ppm is attainable in a laboratory or other test setting, such detection is not currently available in the field with an accurate, portable, reliable, fast and/or inexpensive sensor. Examples of known means of detecting sulfur at ultra-low levels include flame photometry detection (FPD) and inductively coupled plasma (ICP) devices, both of which are appropriate for use in a laboratory setting because of the size of the equipment and the duration of the test cycles.
Accordingly, there is a need for sulfur measurement systems that are compact, easy to use and that are capable of fast measurements of sulfur compound concentrations in diesel fuels by equipment operators in the field.